The long range goals of this research are to ascertain the endocrine mechanisms responsible for the interruption of reproductive function in women engaged in vigorous exercise training or moderate training with dietary inadequacies. Extending previous work, exercise intensity will be moderated somewhat, the subjects being engaged continuously in basic training of low intensity, which is increased only during the follicular or luteal phases of successive cycles. Menstrual and endocrine phenomena (urinary excretion of reproductive hormones and free cortisol) will be followed, as well as the bioimmuno-ratios of LH and FSH in serial plasma samples and LH pulse characteristics at the beginning and end of training. Follicular development will be monitored by ultrasound. The complementary role of dietary factors in athletic menstrual disorders will be investigated by making similar observations in women subjected to varying degrees of dietary deprivation throughout an exercise training program of moderate intensity.